1. Technical Field
This present disclosure relates to an optical chip for detecting fluorescence and optical sensor configurations that utilize an optical chip.
2. Description of the Related Art
There is an increasing requirement to detect a wide range of biological analytes in an aqueous environment with high sensitivity. Lab-on-a-chip designs are widely used for simultaneous and parallel detection of multiple analytes. Most sensors use an optical chip having surface-bound molecules such as antibodies or oligonucleotides that can specifically bind the analytes of interest found in the aqueous solution that flows over the sensors. The sensors typically consist of a substrate having a luminescence emitter in optical contact with the optical detection device. The emitter may transmit luminescence directly into the detection device, or it may require activation by another means (e.g., incident “excitation” light or a chemical reaction).
The majority of current sensor designs have limited sensitivity because they employ rather inefficient techniques for the collection of luminescence emitted by thin sensing films and surface-attached molecules. The problem of low luminescence intensity has been addressed in a variety of ways. For example, the incorporation of metal coatings or metal nanoparticles into sensors increase the intensity of luminescence emitted by molecules in the vicinity of the metal. This technique has been shown to enhance the quantum yield by 100-1000 fold. While somewhat successful, these methods address only increasing the magnitude of the fluorescent signal. Little progress has been made to increase the efficiency of the luminescence collection.
The most sensitive detection technique in widespread use is fluorescence microscopy which is capable of single molecule detection (SMD). Widespread application of SMD is limited because of the expense of the microscope required and its lack of portability. Thus, there is a need for inexpensive, portable, and sensitive devices for fluorescence detection.